The tire pressure indicator of this invention is classified in Classes 340/58 and 200/61.25.
Robinson, in U.S. Pat. No. 3,588,813 issued June 28, 1971, discloses a tire pressure sensing device having a floating spring-biased piston moveable between axial positions corresponding to normal and abnormal tire pressures, and is mounted within the profile of a tire wheel rim. A flexible diaphragm having one side exposed to tire pressure and its opposite side engaging the piston, provides an electrical contact signaling abnormal tire pressure. Furlong, in U.S. Pat. No. 3,588,814 issued June 28, 1971, discloses means for converting tire rotational speed into signals whose values will be proportioned to tire speed of rotation and to the inflated condition of the tire. Dikoff et al disclosed in U.S. Pat. No. 3,568,145 issued Mar. 2, 1971, a sensor for tire pressure having one end of a conductor connected with a power source, with the second conductor end disposed to contact a tire rim on tire deflation. The sensor contact with the rim provides a signal. In U.S. Pat. No. 3,538,271 issued Nov. 3, 1970, Mirsky discloses a tire pressure indicator with mercury switches having vertically spaced contacts.